Quantum key distribution (QKD) is a technique of securely sharing an encryption key between a transmitting node that successively transmits a single photon and a receiving node that receives a single photon while the nodes are connected by an optical fiber. There is also known a technique where a node generates a random number (encryption key) independently of the encryption key shared by QKD and transmits the generated random number to another node for sharing.
In the related art, however, the encryption key is shared after an application or the like makes a request for the encryption key. Accordingly, there has been a problem of processing delay that occurs until the encryption key is used by the application or the like making the request.